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Tuesday, May 3, 2011

US Nuclear Plant News; Browns Ferry, Nine Mile Point

BROWNS FERRY NUCLEAR PLANT

As of late last evening, Browns Ferry has recovered two 161 KV outside lines, and with that has exited the LOOP event criteria which has existed since the 27th of last month following severe tornado damage in the general vicinity. As of this time, the 500 KV grid line has not been recovered, and two diesels are described as not operable but available. The other six diesels are presently fully operable and are in standby (auto-start). Until recovery of the 500 KV line the three reactors will remain shut down in hot standby. There is not yet an expected time/date for the recovery of this system, which is understandable given the wide derangement of the physical distribution system.

NINE MILE POINT

Last night at 8:51 PM, Nine Mile Point Nuclear Station Unit 1 (General Electric BWR/2, Mk I containment) experienced a reactor protection system triggered full scram from 47 percent power. All post-scram plant functions were normal, and the plant is in hot shutdown at this time. Unit 2 was not affected. The significant point with this situation is that the operators do not have any "first out" indication from the protection system, meaning that they don't know why the plant scrammed out. The investigation continues today to determine the actual cause for the scram. In the vast majority of cases such as this, there is a problem with the protection system even if multiple channels of protection are required to scram, and not an actual problem with the reactor plant itself. It is possible also that operator error occurred. We'll keep an eye on this and report findings when Nine Mile Point updates either the press or the NRC.